The present invention relates to the food packaging art, and more particularly to a sliding lid closure for a container for packaging food.
There is a considerable market for low cost, disposable containers for packaging food wherein the containers protect the food packaged therein during transportation and refrigeration, and additionally, may be used for heating and serving the food. Moreover, with the development of thermally stable polymers and paperboard for use in conventional and microwave ovens, disposable food packages prepared from such materials are finding increased popularity.
In general, containers of the class described disclosed in the prior art comprise trays or the like which may be prepared on high speed forming equipment. Some of these trays include integral closure tops, but most utilize separate closure members that in most cases are adhered to a flange element around the edge of the tray. In those cases where the tray tops are adhered to the tray and it is desired to heat the contents of the tray, problems occur when, upon heating, the contents generate gases which must be released. Obviously, if the internal pressures created by the gases are not relieved, the tray may be unattractively deformed and may burst. To avoid these undesireable results, the prior art teaches several methods based on the timely venting of the container. These methods include the use of heat sensitive adhesives for bonding the top closure lids to the tray and meltable plugs which dissolve at high temperatures to provide a vent. In other cases, the tray lid is designed to expand to create an internal space within the container to relieve the increased pressure. And in still other cases, the lids remain sealed to the tray during the entire heating process. Thus, although the prior art teaches products similar to the product disclosed herein, most have been found to be unreliable and difficult and/or expensive to manufacture. Accordingly, in order to overcome the difficulties of the prior art, the present invention discloses a sliding lid for such trays wherein the lid forms a snug but not a pressure tight fit on the tray. Because of this loose fit feature, the contents of the tray can readily be heated without creating problems. Moreover, since the lid of the present invention is easily applied and removed, it is more versatile and finds greater utility than the lids disclosed in the prior art.